Frangible staple



Nov. 4, 1958 M. E. O'CALLAGHAN 2,859,430

FRANGIBLE STAPLE Filed March 2, 1956 352517 a: (Michael E U'CaZZa han 947, Qwmmdy- Mm 22275:

United States P tent FRANGIBLE STAPLE Michael E. OCallaghan, Chicago, Ill.

Application March 2, 1956, Serial No. 569,051

2 Claims (Cl. 340-274) This invention relates to improvements in safety latching devices and refers particularly to a latching device which may be easily shattered or broken by one in an authorized position to do so to effect a release of the means latched, but which will offer appreciable resistance to release-to one not in an authorized position to do so.

For purposes of safety, many municipalities prohibit the permanent padlocking of doors of places of business during business hours or while employers are at work. Frequently, such doors are normally unattended or may be located at portions of the plant or store where employees are seldom near. Such doors, being unattended and unlocked can readily be entered by unauthorized persons and, hence, such business houses are vulnerable to theft.

As an important feature of the present invention a staple or eye-member is contemplated which may be employed with a. conventional hasp and padlock, the staple or eye-member being constructed of a frangible material which is relatively weak in impact, torsion or bending but which is relatively strong in tension.

Another important feature of the present invention resides in a frangible staple or eye-member of the character described which may carry a current-carrying electric wire which when the staple or eye-member is broken, by bending, torsion or impact, is severed whereby an andible or visual alarm is sounded, the operation of the alarm indicating that either the staple has been broken by an authorized person for purposes of effecting an exit, for instance, in the case of fire, or that the staple has been broken by one making an unauthorized entry.

Other objects and advantages of the present invention will be apparent from the accompanying drawing and following detailed description.

Fig. l is an elevational view of a door having a padlock carried by my improved staple, the door being viewed from the inside of a building.

Fig. 2 is a perspective view of my improved staple.

Fig. 3 is an elevational View of the rear of the staplecarrying plate.

Fig. 4 is a diagrammatic view of an alarm wiring diagram which may be used with my staple.

Referring in detail to the drawing, and for purposes of illustrating the use of the invention, 1 indicates a portion of the wall of a building having a doorway 2. A door 3 is positioned in the doorway 2 and may be of the conventional hinged type. In Fig. l the door is viewed from inside the building, said door opening inwardly into the building. The door may be provided with the usual knob 4 and may be provided with a permanent lock 5 which may be employed to securely lock the door by means of the usual key after business hours or when no one is at work in the building.

However, during business hours or when workers are in the building, it is unlawful in many jurisdictions to maintain the door locked by the lock 5 even though the key is made available from the inside of the building since such keys are frequently lost or misplaced.

p Ice 2,859,430

In the present invention a conventional hinged hasp 6 is mounted upon the door 3, said hasp cooperating with a staple or eye-member 7, comprising the present invention, which may be mounted upon the door frame 8 and with which a conventional padlock 9 may cooperate.

The staple or eye-member 7 comprises the important feature of the present invention and is shown in enlarged detail in Figs. 2 and 3. The staple or eye-member 7 comprises a base plate 10 provided with screw holes 11 whereby it may be secured to a supporting surface, as, for instance, the door frame 8. A staple portion 12 may be mounted upon the plate 10 and is provided with an eye 13 through which the keeper of a conventional padlock may be positioned. The usual hasp 6 is provided with a slot (not shown) through which the staple portion 12 may protrude, the slot usually having a width of about five-sixteenths or three-eighths inch in width. Hence, the staple portion 12 will be of a width such as to freely pass through the hasp slot, that is, it will be in the neighborhood of about one-quarter or five-sixteenths inch wide.

Of course, it is to be understood that the specific dimensions hereinbefore set forth are not intended as limitations, but are merely set forth as examples to more clearly exemplify the invention.

As a feature of the present invention the staple portion 12 is constructed of a frangible material which is relatively weak in impact, torsion or bending but which is relatively strong in tension. For instance, the staple portion 12 may be constructed of glass, hard rubber or a plastic material such as polystyrene, polymerized methyl methacrylate or the like. As will be hereinafter more fully described, the material comprising the staple portion 12 is preferably electrically non-conductive.

The base plate 10 is preferably formed integral with the staple portion 12 being constructed of the same material comprising said staple portion whereby the entire eye-members 7 may be cast as a unit. However, if desired, the base plate may be constructed of a material different from the staple portion since it need not be con structed of frangible material.

In employing the present invention, during business hours or when employees are present in the building, the door 3 may be closed with the lock 5 in unlocked position. The hasp 6 may be positioned over the staple portion 12 and a conventional padlock may be secured to said staple portion. If an emergency arises, such as a fire in the building, the staple portion 12 may be readily broken, for instance by grasping the padlock and twisting it, the material comprising the staple portion being weak in torsion or bending, or by giving the staple portion a blow with a hammer, wrench or other implement, the staple portion also being weak in impact strength. Hence, the employees may readily leave through the doorway 2.

However, an unauthorized person seeking to gain entrance to the building can exert essentially a tensional force upon the staple portion 12, although conceivably a degree of impact upon the staple portion may be exerted. However, the unauthorized person is at a decided disadvantage in exerting the type of force required to shatter the staple portion and in most cases would have to create such a disturbance as to be detected by those within the building.

As another feature of the present invention, an electric wire 14 may be embedded in the staple portion, the wire preferably being molded in said staple portion and looping around the eye 13. The ends of the wire 14 may be brought out at the rear face of the base plate 10 at two exposed contacts or terminals 15.

The terminals 15 may be connected to a suitable alarm circuit 16 which for purposes of illustration may comprise a first source of current 17 connected by means of conductors 18 and 19 to a terminal 15 and one end of a Patented Nov. 4, 1958 r relay coil 20, the opposite end of the relay coil being connected by conductor 21 to the other terminal 15. The coil 20 may comprise a portion of a relay switch 22 of the normally closed type, the switch arm 23 being biased by spring 24. The relay switch 22 may be connected in circuit with a second source of current 25 and an alarm 26 of the audible or visual type. A manually controlled master switch 27 may control the circuit comprising the alarm 26.

In operation, while the staple portion 12 remains intact, the circuit to the relay coil 20 will be closed and switch 22 will be open. However, if the staple portion is shattered, wire 14 will be broken, deenergizing the coil 20 and releasing arm 23 thereby closing the alarm circuit. Thus, when the staple portion is shattered an alarm signal is produced.

If the alarm is caused by an authorized person breaking the staple portion 12 other employees in the building will be warned that such an emergency exists as to cause the authorized person to shatter the staple portion. Such a signal is most desirable from the viewpoint of safety. On the other hand, if the staple portion is broken by an unauthorized person operating from outside the door 3, the alarm will also alert the occupants of the building and in doing so will effectively prevent theft.

Preferably the ends of conductors 18 and 20, connected to the terminals 15, may terminate in fixed spaced terminals (not shown) upon the door frame or the like and the terminals 15 may be extended slightly from the rear face of the base plate so that tightening the fastening means which extend through the holes 11 will mechani cally joint the respective terminals together to complete the circuit to the coil 29. Thus, without being required to engage in an extensive wiring operation, the mere replacing of a broken staple or eye-member 7 will complete the circuit to the coil 20.

Of course, the circuit components comprising the wiring system may be positioned adjacent the door 3 or may be positioned at any desired remote location.

I claim as my invention:

1. An eye member constructed of a relatively frangible electrically non-conductive material which is relatively weak with respect to impact, torsion and bending stresses and is relatively strong with respect to teusional stresses, an electric wire embedded in said eye-member and looped around the eye in said eye-member whereby breakage .of said eye-member breaks said electric wire, and terminals at the outer portion of said eye-member for connecting said wire in an electrical circuit.

2. An eye-member comprising a relatively flat plate for mounting said eye-member upon a supporting surface, a staple portion carried upon the front face of said plate for protrusion through the slot in a hasp, said staple being provided with an aperture for the reception of a padlock, said staple being constructed of an electrical insulating material which is frangible and relatively weak with respect to impact, torsion and bending stresses and relatively strong with respect to teusional stress, an electric wire embedded in said staple and looped around said aperture, the opposite ends of said wire being exposed at the rear face of said plate.

References Cited in the file of this patent UNITED STATES PATENTS 597,891 Walstrom Jan. 25, 1898 888,335 OConner Mar. 31, 1908 1,195,493 Nedrow Aug. 22, 1916 1,312,191 McDonnell Aug. 5, 1919 1,797,634 Bruce Mar. 24, 1931 1,873,644 Harbert Aug. 23, 1932 2,363,344 Livenick Nov. 21, 1944 2,668,729 Watters Feb. 9, 1954 OTHER REFERENCES Popular Mechanics, February 1948, page 193. 

